1. Field of the Invention
The present invention relates to a speaker unit and a speaker apparatus, and is applicable to a so-called slim-type speaker, for example.
2. Description of the Related Art
As shown in FIG. 1, a common speaker unit 1 has a speaker diaphragm 2 in an almost conic shape in that the top is opened. The outer circumference part of the speaker diaphragm 2 is supported by a frame 3 via an edge 4. On the other hand, the opening part of the inner circumference of the speaker diaphragm 2 is supported by a damper 5 attached to the frame 3. Thereby, the speaker diaphragm 2 is attached to the frame 3 freely movably in the backward and forward direction.
The speaker diaphragm 2 is fixed to a cylindrical voice coil bobbin 6 on which a voice coil 7 made of a lead wire is wounded at the lower side of its opening part, and is attached in the state where a hemispherical head cap 2A projects in the widely opening direction of the speaker diaphragm 2 so as to cover the opening part at the upper side of the opening part. Thereby, transform in the diameter direction of the above speaker diaphragm 2 and entry of dust or the like is prevented.
In the speaker unit 1, a magnetic circuit part 13 for vibrating the speaker diaphragm 2 back and forth is fixedly attached on the bottom side of the frame 3. This magnetic circuit part 13 has a yoke 10 in a disk shape on that a cylindrical pole piece 10A is planted up from the center. A magnet 9 in a ring shape is fixed as surrounding the top outer circumference of the above yoke 10, and a plate 8 in a ring shape is fixed as layered on the magnet 9.
In the speaker unit 1, if the magnetic circuit part 13 is attached to the frame 3 as a result that the top of this plate 8 and the bottom of the frame 3 are fixed, the voice coil bobbin 6 on which the voice coil 7 is wounded is held as surrounded in the state of being untouched in a magnetic gap g1 formed between the pole piece 10A and the plate 8.
Thus, in the speaker unit 1, if electromagnetic force is supplied to the voice coil 7 of the magnetic circuit part 13 by apply current based on an audio signal supplied from the outside via a terminal 12 and a flexible wire (that is generally called a “kinshisen” in Japanese) 11, the above voice coil 7 is attracted or repelled to the magnet 9. Thereby, the speaker diaphragm 2 vibrates back and forth, and a sound wave corresponding to the audio signal is generated.
By the way, in recent years, further slimming a speaker unit 1 has been desired, and a so-called slim-type speaker unit having a configuration that a thin diaphragm is combined with the end part of a voice coil bobbin having the form of a thin plate, not the aforementioned speaker diaphragm 2 in an almost conic shape in the speaker unit 1, has been proposed (see Japanese Patent Laid-Open No. 2002-223495, for example).